1. Field of the Invention
The invention relates in general to a display and pixel circuit thereof, and more particularly to an organic light emitting diode (OLED) display and pixel circuit thereof.
2. Description of the Related Art
Referring to FIG. 1, a circuit diagram of a conventional OLED pixel circuit is shown. An OLED pixel circuit 100 includes metal oxide semiconductor (MOS) transistors T1˜T4, a capacitor C1 and an OLED O1. When the MOS transistors T1 and T2 are turned on, data Idata is inputted to the pixel circuit 100. When the MOS transistors T1 and T2 are turned off, the capacitor C1 has stored data to light up the OLED O1.
However, in order to turn off the MOS transistor T2, the gate voltage of the MOS transistor T2 has to be decreased and thus the voltage at node A drops down due to a clock feed through effect. The clock feed through effect affects the voltage level of the capacitor C1 and results in luminance variation of the OLED O1.
Referring to FIG. 2, a circuit diagram of another conventional OLED pixel circuit is shown. A pixel circuit 200 includes MOS transistors M1˜M5, a capacitor Cs and an OLED O2. In order to eliminate the clock feed through effect, the pixel circuit 200 controls the MOS transistor M2 by a signal S1 and controls the MOS transistor M3 by a signal S1B with an inverse phase to the signal S1. However, the pixel circuit 200, as compared to the pixel circuit 100, requires an extra MOS transistor, thereby reducing aperture ratio and increasing cost.